Clutch



Au 26, 1941. T. B. MARTIN 2,253,716

CLUTCH Original Filed Jan. 15, 1937 2 Sheets-Sheet l Jnar/ibv 1941- T. B. MARTIN CLUTCH ori inal Filed Jan. 15. 1957 2 She ts-Sheet 2 INVENTOR.

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Patented Aug. 26, 1941 UNITED STATES PATENT OFFICE Bendix Aviation Co rporation, South Bend,

1116., a corporation of Delaware Original application January 15, 1937, Serial No.

Divided and this application June 10,

1939, Serial No. 278,531

4 Claims. (Cl-192-47;

The present invention relates to clutches and more particularly to self-tightening or servo types of clutches.

The present application is a division of the application of Martin Serial Number 120,700, filed Januaryv 15, 1937, which application issued on August 1,1939 as Patent Number 2,167,346.

It is an object of the present invention to provide a novel form of self-tightening clutch which is simple and rugged in construction while being efficient and reliable in operation.

It is another object to provide such a device in which the self-tightening action of the clutch may be automatically or semi-automatically controlled. I

A further object of the invention is to provide such a device which is adapted to engage without shock, drive without slipping,]andrelease without sticking Further objects and advantages will be ap- I parent from the following description taken in connection with the accompanying drawings in which:

Fig. l is a vertical substantially mid-sectional view of a transmission incorporating an automatically controlled and a manually controlled clutch constituting a preferred embodimentof the present invention;

Fig. 2 is a section taken substantially on the line 2-2 of Fig. 1; I

Fig. 3 is a detail inperspective showing the parts of the automatically controlled clutch in disassembled relation; and

Fig. '4 is a perspective detail partly broken away of the driven member of the manually controlled clutch.

In Fig. l of the drawings, there is illustrated a' driving motor I of conventional type comprising a casing 2 in which is journalled a drive shaft 3 extending axially therefrom. A gear housing '4 'is mounted on the end of the motor casing by suitabl means such as indicated at and is provided with an axially extending bearing 6 in which is mounted a driven shaft 1 located substantially coaxial with the drive shaft 3. A pinion 8 or other suitable power take-off member is fixed on the extended end of the driven shaft 1 for the purpose of transmitting power therefrom to the apparatus, not illustrated, which it is desired to actuate.

Two trainspf gearing are provided in the gear housing 4 for optionally connecting the drive shaft 3 to the driven shaft 1 at two different gear ratios. As here illustrated, the low geartrain includes a pinion 9 mounted on the drive shaft 3 and fixed thereto in any suitable wayas by means of a pin I I'traversing the drive shaft and the hub I2 of the pinion. A transmission mem- .freely mounted on a smooth portion'll of a lay shaft I5 journalled at its ends in the motor casing 2 and gear housing 4 in parallel relation beneath the driving shaft '3 and driven shaft 1 i ,and is driven at low speed from driving shaft 3 through the low speed pinion 9 and transmission member I3. A pinion I6 is fixed on the lay shaft -in any suitable manner asindicated at I1 and is arranged to mesh with a gear l8 keyed as indicated at IS on the driven shaft 1.

Lay shaft I5 is driven at low speed from the driving shaft 3 through the low gear train comprising pinion 9 and transmission gear I3 by means of, an overrunning clutch connection between gear I3 and shaft I5 comprising a clutch member in the form of a clamp nut 2| threaded on the lay shaft as shown at" 22 and having a plane surface 23 arranged to frictionally engage and bind against the adjacent side of the transmission gear I31 I Means for controlling the action of the clamp nut 2| is provided in the form of a. spring detent member 24 bearing frictionally on the periphery of said nut and non-rotatably connected in any suitable manner as indicated at 25 to the transmission gear member I3. The design of these parts; including the pitch and mean radius of the threaded connection 22 and the mean radii of the contacting surfaces of the nut and gear, is such that forward rotation of the transmission gear I3 causes the clutch member 2| to clamp said gear against a thrust washer 26 on the lay shaft I5 and thereby cause the gear to drive said shaft at low speed.

It will be understood that the engaging surfaces of the clutchmember 2| and gear I3 may be roughened or serrated inany suitable manner in order to break down the oil film therebetween and/or render the clutch more positive in action if deemed desirable A high speed gear drive is provided between the J drive shaft 3 and the lay shaft I5 including a drive gear 21. loosely mounted.v on the extended hub 28' of the drive pinion 9. The drive gear 21 is arranged. to mesh with a driven pinion 29 keyed .to the lay shaft I5 'asindicated at 3|. Pinion29 is clamped against the thrust washer 26 which is seated against a shoulder 30 on the lay shaft,

by means of a nut 32 threaded on said shaft. A

lock washer 33 is preferably located between the nut 32 and gear 23 to prevent the nut from working loose.

Meamsubject to automatic or semi-automatic control for driving the high speed gear 21"from the drive pinion- 9 is provided in the form of a friction clutch comprising discs 34 and 35 splined respectively to the hub of the'pinion 9 and the interior of the gear 21. These clutch discs are arranged to be brought into frictional engageber in the form of a low speed driven gear I3 is ment by means of a control member in the form of a nut 36 threaded on the end of the driving pinion hub as indicated at 31 and arranged to clamp the discs against a thrust washer 33, bearing against a shoulder 39 formed on said pinion.

Means for controlling the clamping action of the clutch control nut 36 is provided in the form of a spring detent member 4| frictionally mounted .on the periphery of said nut and normally rotatable therewith and having a terminal projection 42 extending radially in the plane of a detent member 43 slidably mounted .in the gear housing 4. The detent 43 may be projected, manually into the .path of the projection 42 bypressure upon desired.

The elements of the high' speed clutch are so proportioned and arranged that when the friction spring member 4| is arrested in its movement by the detent 43, the retarding effect thereof will cause the control nut 36 to blcse the disc clutch.

and connect the drive gear 21 non-rotatably to the drive pinion 9 and consequently to the drive shaft 3. When the friction member 4| is released, however, the pressure of the control nut 33 against the clutch member is relaxed, and the. gear 21 will be freed from the drive shaft '3. If desired, a dished spring member 45 may be interposed between the control nut 36 and the gear 21 in order to assist the relaxing motion of said nut. Y

It will be appreciated that inasmuch as the friction of the spring member 4| is a parasitic drag during high speed-operationotthe transmission, it is desirable to use as light pressure "thereof as is consistent with reliable control of the transmission. One example of structure which has been found satisfactory in service comprises a thread of about one-half to three-quarters of an inchdiameter and eighteen degrees to twenty degrees pitch, a friction surface of about one and one-quarterto one and one-half inches average diameter on the'control nut, and a, con-.-

' trol torque of about two inch pounds.

In the operation of this device, when the motor is energized while the detent is in its retracted position as illustrated in Fig. 1, rotation of the drive shaft 3 is-transmitted' through pinion 9 to gear l3. consequent rotation of the friction spring 24 causes the control nut2| to clamp the gear |3 to the lay shaft 5, causing said lav shaft to rotate and operate the driven shaft 1 through pinion l6 and gear I8 whereby the pinion 8 is caused to drive the de'vice to be operated at low speed k 7 When it is desired to operate the device at high speed, it is merely necessary to project the de-" tent 43 into'the path of the terminal 42 of the friction member 4|. A retarding efl'ect is thus sleeveha clutch member threaded thereon, a sechereto.

2's and thus causing the drivenshaft 1 to be operated at high speed. When it is desired speed clutchis released, however, the low speed clutch will automatically re-eng'age as previously described, and the low speed drive will be resumed.

- Although but ,two forms of clutch embodying the invention have been shown and described in detail, it will be understood that other embodiments are possible and various changes may be made inthe design and arrangement of the parts without departing from the spirit of the invention as defined in the claims appended What is claimed is: I

1. In a transmission mechanism, a driving member, adriven member and a disconnectable connection therebetween including a clutch member threaded to the driven member and arranged to have a frictional connection with the driving member, and a yielding element anchored to the driving member and bearing frictionally on the clutch member to thereby operate the threaded connection to close the clutch for transmitting rotation from the driving member'to the driven imparted to the control nut 36 which conse-# tion of the friction member in closing the clutch.

Gear 21 is'thus caused to rotate with the drive shaft 3, driving'the lay shaft through the pinion member, andto open the clutch when the driven member overruns the driving member.

2. In a transmission mechanism, a drivingmember, a driven member, connecting means therefor including friction clutch elements connected respectively to said members, a control member having a threaded connection to the driving member such that retardation of the control member causes engagement of the clutch elements,.a spring bearing frictionally on the control member and normally rotatable therewith, and manually operable means for arresting the rotation of the spring to thereby retard the control member and cause engagement of the clutch elements.

3. In a transmission mechanism, a driving member, a driven member and a disconnectable connection therebetween including a clutch member threaded to one of said members and'arranged to frictionally engage the other member,

and means including a coiled spring member bearing fri'ctionally on the clutch member and adapted to be wound down on the same to apply torque thereto'in a direction to cause the clutchmember to thread itself into frictional engagement with said other member.

4. A self-tightening clutch including a screw and clutch member frictionally engaging the first .clutch member rotatably but non-slidably mounted with respect to the screw sleeve, and a self-tightening'coiled spring detent mounted to rotate with one of said' clutch members and frictionally connected to the other olfitch member to control the engagement oi' the clutch; members.

' THOMAS B. MARTIN. 

